Chances are it won't reflect the cultvar it came from, but it could be suitable for grafting a specific cultivar onto.

I say 'could' because, with cultivated apples, both top (trunk and upwards) and bottom (roots and base of trunk) tend to be cloned from carefully selected cultivars. That selection is for particular qualities, eg. dwarfing rootstock, fruit suitable for cooking. Of course there are a great number of apple fruit cultivars.

In your case, the tree is clearly growing well, so it it not having difficulty with the soil. So, if you do not need a dwarf tree, you could either let it grow, and treat it as an ornamental (the blossom should be nice anyway), or try grafting a particulr cultivar onto it (or getting somebody with experience to do it for you).